Despite its antiquity, the process of burial of human and animal remains is still a source of unsolved problems and an area of technology in need of innovative solutions. The needs exhibit a unique combination of satisfaction of emotional desires, cultural and religious imperatives, aesthetic considerations and modern health and anti-pollution regulations.
It is often desired to display the remains of the deceased reposing in an aesthetically pleasing surrounding for memorial services or other rituals. The materials in contact with the remains are desirably fabrics pleasing in appearance but these are subject to rapid deterioration after interment. The basic containers for the remains and such materials, referred to as caskets, are usually of wood, metal, plastic, fiberglass or other materials such as cultured marble which are finished to provide an aesthetically pleasing appearance. It is desirable for caskets to be light in weight to facilitate movement of the remains generally and, more particularly, in a dignified fashion during ceremonies. Generally such characteristics are at least to some extent incompatible with structural strength and durability after interment. Wood and metal caskets are particularly subject to underground deterioration.
Consequently, in many jurisdictions it is required that caskets be interred within burial vaults, usually of concrete, designed to withstand the immediate forces of covering the remains with earth, the continuing static load of the earth and movement of equipment over the gravesite. Thus, subsidence of the earth over the gravesite and the possibility of toppling of nearby monuments are minimized and crushing of the casket and remains is prevented.
In many cultures it is considered desirable that the remains be preserved as long as possible even after burial. This desire is consistent with the present-day need to prevent the products of the inevitable putrefaction of the remains, such as formic acid, from escaping from the gravesite and contaminating the environment. Similar needs and desires exist with respect to above ground interments where vaults may not be required for support reasons. Neither concrete vaults nor most of the caskets described above are impervious to the entry or exit of liquids, gases or organisms which could defeat these needs and desires.
Therefore both vaults and caskets, both referred to herein as interment containers, have been provided on their interiors with linings of various materials in attempts to meet those needs. The addition of linings of any material to a structure is a labor-intensive and expensive process. Therefore, an important objective of improvements in this art is to provide layered preformed structures using processes such as vacuum forming, casting or molding, which are less labor intensive than custom construction, and which produce a product which can serve as an interment container. These preformed structures may be used with or without additional work or materials being added. Herein, such structures are referred to as interment container liners in accordance with general usage, and are to be distinguished from "linings" which are merely attached to the interior or other structures. However, it should be understood that a structure in accordance with this invention may serve as an interment container without addition in some uses and the use of the word "liner" should not be construed to limit the invention.
Various materials have been proposed and used for both interment container linings and liners. For example, plastic liners are shown and referenced in U.S. Pat. No. 4,314,390. In this patent it is suggested that plastic liners can serve as an inner mold, outer mold or both for a concrete or aggregate vault. Lining materials or interment container liners of fiberglass or fiberglass containing mixtures have also been proposed. See, for example, U.S. Pat. No. 3,839,768. The use of either plastic or fiberglass liners is disclosed in U.S. Pat. No. 3,787,545. These references are offered as examples and are not to be considered exhaustive of the art.
Both plastic and fiberglass have relative advantages and disadvantages as materials for interment container liners. Plastic is more easily extruded into a sheet and vacuum formed into a container or liner shape. Its cure time, if any, is short and it is light in weight, reducing shipping costs. However it is not as strong or rigid as fiberglass and is often penetrable by water, gases and microorganisms. Fiberglass compositions on the other hand are usually impervious to water, gases and microorganisms. They are stronger and more rigid than plastic and are generally considered to result in a superior product. However, the liners which can be constructed using them are substantially heavier than comparable liners of plastic, resulting in increased shipping costs, and take longer to manufacture, in part because of long cure times, which increases their cost.
Viewing the prior art, as exemplified by the patents mentioned above, and the relative advantages and disadvantages of various materials for interment container liners, applicant conceived of a liner which would combine the advantages of both plastic and fiberglass and in which the disadvantages of one material would be compensated by the advantages of the other by laminating a plastic and a fiberglass layer to one another to form the liner. Applicant's search of the art, even after the invention, has not discovered any suggestion of this combination.
Applicant's initial discovery was not without problems. Layers of fiberglass composition and plastic appeared to have a tendency to delaminate, thus forming voids between the layers which would possibly defeat the purposes of the burial interment container. After investigation, Applicant discovered that in a completely dissimilar art, that of refrigerators, fiberglass was used as a thermal insulating material, not as a material impervious to fluid transfer and not usually as part of a composition. Yet in this application it was known to be laminatable to plastic layers without resulting delamination. Applicant discovered that the key to preventing delamination was the use of an intermediate layer of acrylic material between the fiberglass and the plastic.